Just pass the array to the Set constructor. The Set constructor accepts an iterable parameter. The Array object implements the iterable protocol, so its a valid parameter. var arr = [55, 44, 65]; var set = new Set(arr); console.log(set.size === arr.length); console.log(set.has(65)); See here
You can create an array with all elements from a given Swift Set simply with let array = Array(someSet) This works because Set conforms to the SequenceType protocol and an Array can be initialized with a sequence. Example: let mySet = Set([“a”, “b”, “a”]) // Set<String> let myArray = Array(mySet) // Array<String> print(myArray) // [b, … Read more
Because sets have no ordering. Some implementations do (particularly those implementing the java.util.SortedSet interface), but that is not a general property of sets. If you’re trying to use sets this way, you should consider using a list instead.
It depends on what you are intending to do with it. Sets are significantly faster when it comes to determining if an object is present in the set (as in x in s), but its elements are not ordered so you cannot access items by index as you would in a list. Sets are also … Read more
If you have a list of hashable objects (filenames would probably be strings, so they should count): lst = [‘foo.py’, ‘bar.py’, ‘baz.py’, ‘qux.py’, Ellipsis] you can construct the set directly: s = set(lst) In fact, set will work this way with any iterable object! (Isn’t duck typing great?) If you want to do it iteratively: … Read more
Update 3/2022 There is currently a proposal to add Records and Tuples (basically immutable Objects and Arrays) to Javascript. In that proposal, it offers direct comparison of Records and Tuples using === or !== where it compares values, not just object references AND relevant to this answer both Set and Map objects would use the … Read more
You can write an object that behaves like a dict quite easily with ABCs (Abstract Base Classes) from the collections.abc module. It even tells you if you missed a method, so below is the minimal version that shuts the ABC up. from collections.abc import MutableMapping class TransformedDict(MutableMapping): “””A dictionary that applies an arbitrary key-altering function … Read more
One reason is that it is easy to create a set from map: s := map[int]bool{5: true, 2: true} _, ok := s[6] // check for existence s[8] = true // add element delete(s, 2) // remove element Union s_union := map[int]bool{} for k, _ := range s1{ s_union[k] = true } for k, _ … Read more
Use the retainAll() method of Set: Set<String> s1; Set<String> s2; s1.retainAll(s2); // s1 now contains only elements in both sets If you want to preserve the sets, create a new set to hold the intersection: Set<String> intersection = new HashSet<String>(s1); // use the copy constructor intersection.retainAll(s2); The javadoc of retainAll() says it’s exactly what you … Read more
For sets: var merged = new Set([…set1, …set2, …set3]) For maps: var merged = new Map([…map1, …map2, …map3]) Note that if multiple maps have the same key, the value of the merged map will be the value of the last merging map with that key.